This project will determine the effects of different doses of nicotine administered via inhalation, transdermal application and gum on human behavior in a controlled laboratory setting. This will allow some comparisons between the behavioral effects of different routes of nicotine administration. The behaviors which we will study are all elicited or controlled by aversive environmental stimuli. Aversive environmental stimuli were selected since data indicate that such stimuli set the occasion for increased self-administration of tobacco and also frequently set the occasion for re-initiation of tobacco self-administration following smoking cessation. To determine the effects of nicotine and tobacco on human behavior in the presence of aversive environmental stimuli we will study: (1) aggressive responding elicited by provocation involving presentation of aversive stimuli, (2) avoidance responding maintained by avoidance of presentation of aversive stimuli and increases in avoidance responding following the presentation of added unavoidable aversive stimuli, and (3) responding suppressed by contingent presentation of aversive stimuli, i.e., punishment. These studies will allow us to determine how nicotine may alter behavior generated and maintained by interaction with aversive environmental stimuli. Such effects may underly one of the major reinforcing properties of nicotine. The project will also examine changes in aggressive and avoidance responding during acute tobacco withdrawal. These studies will add information concerning changes in behavior associated with tobacco withdrawal. Nicotine gum and placebo gum will be administered during tobacco withdrawal to determine their effects on these changes in behavior during tobacco abstinence.